It has expanded Omnicom-owned Agency Republic's responsibility to cover all consumer online advertising, having asked it to promote BT Broadband in September.
Agency.com has been given business online advertising, while Oyster Partners now has sole responsibility for web design and development.
"We needed greater focus. Now we have a clearer delineation of roles," said BT's head of marketing and communications, Catherine Kehoe.
The move could squeeze Ogilvy Interactive's relationship with BT, although Kehoe said it would continue to work with the agency on "strategic initiatives".
The shake-up does not affect BT's online media planning and buying requirements, mainly handled by i-level.
Meanwhile, BT Retail has shortlisted shops to pitch for a place on its above-the-line roster. It wants a third agency alongside St Luke's and Abbott Mead Vickers BDDO (Marketing, September 19).